Motion picture projector



Feb. 15, 1944. R. J. MILLER 2,341,734

' MOTION PICTURE PROJECTOR Filed March 15, 1941 3 Sheets-Sheet l INVENT OR. BY Ear/102m MM :e

Feb. 15, 1944. R. J. MILLER MOTION PICTURE PROJECTOR Filed March 15, 1941 3 Sheets-Sheet 2 INVENTOR. Payne/v0 1/7/4456 ,477'0E/VJ Feb. 15, 1944. R. J.

MILLER 2,341,734

MOTION PICTURE PROJECTOR Filed March 15, 1941 3 ShetS-Shtiet 3 x 2 288 i 4 zas 290 79 2y I :aQ

' INVENTOR. Ea nvo/vo J/I/LL 5e ATTOP/Vf) Patented Feb. 15, 1944 MOTION rrc'ruas raomo'roa Raymond J. Miller, Detroit, Mich, asslgnor to American Pattern and Manufacturing (30., Betrolt, Micln, a copartnersliip consisting or said Miller and Alfred E. Wilson, Detroit, Mich.

Application March 15, 194i, Serial No. 333,5..3

(Cl. S s-ll 9 Claims.

This invention relates to motion picture projectors and more particularly to improved means for supporting and actuating the aperture pressure plate housin In the operation of motion picture projectors, independent visual images carried by a continuous strip of film of any suitable material are successively aligned with an aperture and are projected from the film onto a screen by a light directed through the aperture and film. Means such for example as an aperture pressure plate housing having a plurality of spaced shoes may be provided to yieldingly urge the film into engagement with spaced film tracks positioned adjacent the aperture,

It is necessary that the aperture plate housing be movable relative to the aperture pres= sure plate and film tracks to enable the oper= ator to thread the film onto the film driving sprockets employed to drive the film and align successive film frames with the aperture. Heretofore the aperture pressure plate housing has been so mounted that it could, be moved away from the aperture plate against the resistance of a relatively heavy spring employed to yieldingly urge the housing towards the plate, This mechanism has not been satisfactory because the mounting structure has been unstable and unless carefully manipulated the housing would slam against the film tracks and aperture plate injuring the film and subjecting the movable parts of the projector to undesirable sho An object of this invention is therefore to provide a rigid mounting for an aperture pres sure plate housing; wl'iereb; the housing may be moved relative to an aperture in improved manner to enable the operator thread up" the projector.

A further object resides in provision an aperture pressure plate housing support member movahly on e, plure y of spaced rods in such a manner that the housing is accurately maintained in alignment with the aperture plate.

Another object is to provide a horizontally and vertically adjustable support member for an aperture pressure plate housing.

Still another object is to provide a novel aperture pressure plate housing and support member therefor which may be readily removed from the film compartment of a projector, and which desired may be insulated from the projector casing to minimize distortion due to variations of temperature.

Yet a still further object of the invention resides in the provision of improved actuating means for an aperture pressure plate housing whereby the housing may be smoothly and easily actuated and positively locked when in the mechanism o1 3 showing the closed position relative to the aperture plate of the projector.

Another object is to provide an improved and rugged supporting and actuating member for aperture pressure plate housing which may economically manufactured. Other objects and advantages of this invention will be apparent from the following detailed scription considered in connection with the ac companying drawings, submitted for purposes of illustration only, and not intended to the scope of the invention, reference for that purpose to the subjoined claim.

In the drawings wherein similar reference characters refer to similar parts throughout the several views:

l is a perspective vies. of a motion picture projector embodying the present invention 2 is a sectional view of a portion Y device illustrated in s. Fig. 3 is a sectional. view taken sulostantie on. the line of Fig. 2, looking in the s tion of the arrows.

Fig. is an enlarged view oi the ac port member in two operative posi 5 a sectional view simz Before explaining in Get tier? coast-n trated e accompanying s.

cation capable of embodie 0; being practiced or co out Also it is to pisaseology or terminoi to purpose or descr Rewiring new to 3; it served that the invention is illustrates as i embodied in a motion picture projector he main casing it). substantially vertic tending intermediate wall divides t1 within the casing it into a film compsi it a mechanism compartment A substantially vertically extending drive shaft l3 positioned in the mechanism comp t ment it is operably connected through subst :1- tially horizontally extending shafts iii and 2'52 projecting through the intermediate wall 62 actuate film driving sprockets it and 26 havis radially extending sprocket teeth 26 adapter; project through spaced apertures in the film drive the film at a substantially predetermined speed.

T e vertically extending drive Sam I:

mounted in a gear train carrier column 36 and is operably connected through a shaft 32 and an intermittence driving mechanism 34- with an intermittently driven sprocket 36 positioned in the film compartment l4. The sprocket 36 is intermittently driven to momentarily align successive film frames with an aperture 38 formed in an aperture plate 46- carried by an aperture plate housing 4|.

The aperture plate 46 is spaced from a back wall 42, and the aperture 88 is aligned with a light admitting aperture 43 and a shutter housing 44. The shutter housing 44 is preferably provided with a power drivenshutter adapted to intermittently interrupt the flow of projecting light through the aperture and film as the intermittently driven sprocket 36 is actuated to align successive film frames with the aperture 38.

The film is maintained in alignment with the film tracks 45 associated with the aperture plate 46 by a plurality of spaced film engaging shoes 41 yieldingly urged into engagement with the film by film shoe springs 49 carried by a pressure spring carrier plate of the pressure plate housing 46. The film is maintained in contact with the sprocket teeth 28' of the intermittently driven sprocket 36 by an intermittence sprocket shoe-53 carried by the pressure plate housing 46 and adjustably mounted relative to the intermittently driven sprocket 36.

Means are provided to permit movement of the pressure plate housing 46 away from the film tracks 45 and aperture plate 46 to permit the operator to thread the film between the aperture plate housing 4| and the pressure plate housing 46 and into engagement with the film driving sprockets.

One desirable form or such actuating means comprises a pressure plate housing carrier arm 48 slidably mounted on a plurality of vertically spaced generally horizontally extending rods -56. The rods 56 may be secured to a bracket 52 by means of a plurality of screws 55. The bracket 52 may be secured to a fixed portion of the projector such for example as to the intermediate wall I 2 by a plurality of screws 54. If desired, suitable heat insulating material may be interposed between the rods 56 and the bracket 52 and between the bracket 52 and the fixed portion of the projector to retard the fiow of heat.

The carrier arm 48 may be provided with suitable engaging means such for example as a plurality of spaced bosses 56 slidably mounted on the upper rod 56 and a single boss 58 slidably mounted on the intermediate rod 56. The carrier arm is thus supported at a plurality of spaced points, preferably three, whereby a rigid mounting for the pressure plate housing 46 is provided.

A lens carrier bracket 66 preferably mounted on the lower rod 56 at a plurality of spaced points and on the intermediate rod 56 by a single boss 62 may be provided to support a lens carrier tube 64 in alignment with the aperture 38 of the aperture plate 46. The lens carrier tube 64 is thus also mounted in the film compartment M at a plurality of spaced points whereby a relatively rigid supporting structure is provided. It will be noted that the intermediate rod 56 acts as a supporting member for both the aperture pressure plate carrier arm 48 and the lens carrier bracket 66. A strong and compact structure is thus provided.

A lens focusing and locking mechanism may longitudinally on the rods 66 to focus the projected images on the screen. One desirable form of such focusing device comprises a stud 66 mounted in the front wall 68 of the casing l6 and threaded into a boss 16 carried by the lens carrier bracket 66. A manually operable control knob 12 may be provided to actuate the stud 66 to rotate it in the boss 16 to move the lens carrier bracket 66 on the rods 56.

A spring 14 may be interposed between the front wall 68 and the boss 16 to yieldingly urge cooperating male and female thread portions of the stud 66 and boss 16 into engagement thereby in effect giving a micrometer adjustment of the lens carrier tube 64. A locking mechanism 16 may be provided to lock the lens carrier bracket 66 in a substantially predetermined position in the film compartment l4.

Motion transmitting means. may be provided between the pressure plate housing carrier arm 48 and a relatively fixed portion of the projector to move the pressure plate housing 46 away from the aperture plate housing 4| to enable the operator to thread the film into operative relation with the film guiding and driving elements of the projector.

One desirable form of such motion transmitting means comprises a downwardly extending projection 18 having a substantially vertically extending slot 86 formed therein. The slot 86 receives an actuating member such as a roller 82. The roller 62 is mounted on a pin 64 carried by an arm 86 fixed to a shaft 88. The shaft 88 is rotatably mounted in a boss 96 supported by an outvgardly extending projection 92 of the bracket 5 The shaft 88 is provided with an actuating lever 94 and a stop member 96 adapted to be rotatably mounted in a slot 98 formed in the outer edge of the boss 96 to limit rotational movement of the shaft 88 between substantially predetermined limits. Movement of the pressure plate housing 46 away from the aperture plate housing 4| is therefore limited to a desired distance.

It will be noted that the actuating member or roller 62 moves beyond the dead center position in the slot 86 to provide a positive lock to prevent the motion transmitting mechanism from being unintentionally actuated to permit the pressure plate housing 46 from moving away from the aperture plate housing 4| while the projector is operating.

Yielding means may be interposed between the film engaging shoes 41 carried by the pressure plate housing 46 and the actuating lever 94 to compensate variations of thickness of the film such for example as caused by the presence of a patch in the film. Such yielding means may take the form of the film shoe spring 49 carried by the pressure plate housing 46 or may take the form of a spring 99 positioned between the boss 58 of the carrier arm 48 and a relatively fixed portion of the projector such for example as a portion of the intermediate rod 56. Such yielding means cooperates with the locking means formed by the movement of the roller 82 beyond the dead center position in the slot 86 to prevent unintentional actuation of the motion transmit ting means.

The operation of the pressure plate housing 46 is as follows: When the actuating lever 94 is turned in the clockwise direction, it causes the arm 86 to revolve likewise. The roller 82-01! the be provided to move the lens carrier bracket 66 pin 84 carried by the arm 86 moves upwardly in the slot 80 of the downwardly extending projection 18 of the carrier arm 48 and moves the carrier arm forwardly, thus opening the aperture plate housing 4| to give access for threading film into the machine.

When the film is placed in the machine, the actuating lever 94 is rotated in the counterclockwise direction, causing the roller 82 to move downwardlyin the slot 80 to move the pressure plate housing 46 backwardly in th film compartment I4 and closing the aperture pressure plate. As the roller 82 passes the dead center position in the slot 80 as illustrated by the axis H of Fig. 4 and is moved to a. substantially predetermined position such for example as illustrated by the axis b-b of Fig. 4 as permitted by the stop member 96 carried by the actuatin shaft 88, the aperture pressure plate is locked in the closed position. The movement of the stop member 96 in the slot 98 controls the amount of actuation of the pressure plate housing "as above described.

The spring 99 exerts pressure on the actuating arm and the slot and this force is transmitted through the roller 82 to the stop member 96 carried by the shaft 88. The aperture pressure plate housing therefore cannot be forced open by a patch or other obstruction on the film as it passes through the machine, since the pin 84 and the roller 82 are maintained at a point in the slot 80 below dead center of the shaft 88.

The foregoing described construction is shown in larger scale in Fig. 4 in which the dotted line view shows the parts in the positions they occupy when the aperture carrier plate housing is open. The solid lines show the parts in the locked position. The position of the stop member 96 in the slot 98 is here clearly shown.

Means may be provided to mount the pressure plate housing 46 on the housing carrier arm 48 in such a manner that it may be adjusted vertically and horizontally to properly align it with the aperture plate housing 4 I.

One desirable form of such adjustable mounting means comprises an adjustable locking device more clearly shown in Fig. 2. The arrangement of the parts is such as to permit ready removal of the pressure plate housing 46 as a unit from the film compartment I4 of the projector.

The carrier arm 48 is provided with a plate I having a laterally extending pin I03 projecting therefrom. The plate iIlI may be secured to the arm 48 by a plurality of screws I05 projecting through generally arcuate shaped slots in the plate lIlI whereby the plate may be rotated slightly relative to the arm 48 to adjust the vertical position of the pressure plate housing 46 relative to the aperture plate housing 4!, and to adjust the contact position of the intermittence sprocket shoe 53 relative to the intermittently driven sprocket 36.

A male cone E01 may be secured to the piste IOI by a plurality of screws i0!) projecting through vertically extending slots in a flange Hi carried by the male cone I01 whereby the cone can be elevated or lowered slightly relative to the plate I 0| to adjust the vertical position of the pressure plate housing 46 relative to the aperture plate housing M.

The pressure plate housing 46 is provided with a laterally extending female cone ills adapted to receive the male cone I01 and is also provided with an apertured boss i adapted to receive pin I03.

The pressure plate housing 4&3 may be locked and unlocked in position on the male cone I01 by a locking key II1 carried by a locking shaft I59 and adapted to project inside the male cone I91 through a slot I2I. The locking key H1 is actuated by the locking shaft H9 having an actuating knob H3 and is maintained in looking position by the tension of a spring I25.

Frequent removal of the pressure plate lions ing 46 is desirable in order to permit cleaning of the pressure plate; housing and the film tracks and shoes. The removal of the aperture pressure plate housing as a unit is accomplished by turning the locking key II1 from the vertical position to the horizontal position so that it is aliflned with the slot I2I. In this position the locking key I I1 can be withdrawn and the entire pressure plate housing 46 may then b removed from the male cone I01.

In replacing the aperture pressure plate housing the guide pin I03 carried by the adjustment plate I0l enters the aperture of the boss II. The complete alignment is obtained by contact of the female cone H3 and the male cone I01. In assembling the mechanism the housing 46 is pressed firmly back until the female cone I I3 contacts the male cone I01. The actuating knob I28 which actuates the locking key I I1 is then pressed inwardly toward the male cone thereby compressing the spring I25 until the locking key III occupies a position inside the male cone I01. The knob I23 is then rotated and the locking key II1 fits into shallow grooves on the inside of the male cone I01 as illustrated by the position occupied by the locking key II1 of Fig. 3. When the key is moved to the locked position the knob I23 is released whereupon the spring I26 resiliently holds the parts securely in the assembled position because the pressure plate housing 46 is firmly supported and aligned at vertically spaced points on the cooperating cones and by the pin and apertured boss.

The embodiment of the invention illustrated in Fig. 5 is similar in many respects to the embodiment illustrated in Figs. 1 to 4. Corresponding parts have therefore been given corresponding reference numerals with the addition of I00.

The pressure plate housing may if desired be attached to a carrier plate IBI fixed to the carrier arm I48 by means of a bolt I63.

The pressure plate housing carrier arm I40 may be provided with a downwardly extending actuating member I65 having a pair of spaced members I61 and B69 positioned to be engaged by a cam I1I carried by the shaft i88 to move the pressure plate housing carrier arm I48 towards the open and closed positions respectively with reference to the aperture plate housing.

It will be noted that actuating portion of the cam HI engaging the member I69 is permitted to move beyond the dead center position illustrated by the axis aa, to an angular position illustrated by the axis bb, to permit the yielding means such as the film shoe engaging springs or the spring l99 to exert a force to yieldingly maintain the pressure plate housing in the closed position with reference to the aperture plate housing.

When it is desired to move the pressure plate housing from the closed position with reference to the aperture plate housing, the actuating lever 5% is rotated in the clockwise direction from the position illustrated. This rotational movement of the actuating lever is transmitted through the shaft I88 to move the cam I18 in the clockwise direction also. The initial move-- ment of the cam ill moves the actuating surface of the cam which engages the member it?) from the position on the axis 12-1) to a position on the axis H. The yielding means between the car= rier arm ms and the aperture plate housing is compressed as the cam moves beyond the dead center position on the axis aa to render the yielding lock inoperative. Further rotational movement of the cam ill in the clockwise direction exerts a force on the member it'll to move the pressure plate housing carrier arm its on the rods E50 to separate the pressure plate housing from the aperture plate housing to enable the operator to thread film into the projector. The stop member use moving in the slot isii limits rotational movement of the shaft 988 and cam iii and hence the movement of the carrier arm M8 on rods 06b.

The embodiment of the invention illustrated in Fig. 6 is also similar in many respects to the embodiment illustrated in Fig. 3. Corresponding parts have therefore been given corresponding reference numerals with the addition of Ebb.

In this embodiment of the invention the pres-= sure plate housing 266 is illustrated as being de-= tachably connected to the housing carrier arm 2 38 mounted on the rods 2% by means of a plate 275 and a bolt 2W.

The housing carrier arm 251i is preferably provided with a downwardly and backwardly extendlng projection 279 which may be actuated to move the pressure plate housing carrier arm 2% on the rods 2% to open the space between the pressure plate housing 266 and the aperture plate housing 26! to thread film into the projector.

The shaft 2% rotatably mounted in the boss 2% carried by the bracket 252 is provided with an arm 289. The arm Edi is pivotally connected by a pin 283 with a link 2% pivotally connected by a pin 28? with the projection 2% of the carrier arm 2&8.

It will be noted that when the gate or pressure plat housing 2% is in th closed position relative to the aperture plate housing 241i, the pin 2&8 interconnecting the arm 28d and the link 2% lies beyond the dead center position of the toggle connection defined by the axis a-a intercon meeting the center of the pin 287 and the center of the actuating shaft 288. The yielding means between the film engaging shoes and a fixed portion of the projector urges the arm Edi and the 28b to move beyond the dead center position defined by the axis aa. The stop member 29$ carried by the shaft 288 and movable in the slot 29b of the boss 2% prevents the yielding means from urging the links beyond a substantially predetermined position. Irregularities in film thick? ness such as caused by the presence of a patch will therefore not force the gate open because the film engaging shoes can move relative to the film tracks carried by the aperture plate housing RM to compensate for such irregularities.

This is a continuation-impart of my co-pending application Serial No. 250,310, filed January 11, 1939.

I claim:

1. In a commercial motion picture projector having a film compartment including a fixed member, an aperture plate mounted in the compartment, a pressure plate having a plurality of spaced substantially vertically extending engaging shoes slidably mounted on the fixed member andmovable between positions adjacent and spaced from the aperture plate, a movable member mounted on the fixed member beneath said -engaging shoes, a connection between assi se said movable member and the pressure plate comprising motion traitting means -movable beyond a dead center position when the pressure plate is adjacent the aperture plate, yielding meam between the film engaging shoes and the fixed member urging the motion-transmitting means beyond said dead center position to prevent unintentional movement of the pressure plate away from the aperture plate, and manually operable means to actuate the motion transmitting means.

2. In a motion picture projector having a film compartment including a fixed wall, an aperture plate mounted in the film compartment, a bradset carried by the wall, a plurality of spaced rods carried by the bracket, a pressure plate carrier arm slidably mounted on a plurality 'ofisaid rods, a pressure plate housing mounted on the carrier arm, a boss carried by the bracket, a shaft rotat= ably mounted in the boss and having a stop mem= ber movable in a slot of the boss to limit rotational vement of the shaft, a projection on the housing carrier arm, and motion transmitting means between the projection and shaft to move the pressure plate housing between positions adjacent and spaced from the aperture plate.

3. In a motion picture projector having a main casing, a wall dividing the space within the casing into mechanism and film compartments, an aperture plate in the film compartment, a pressure plate housing including film engaging shoes in the film compartment, a carrier arm having a downwardly extending slotted projection supporting the pressure plate housing, connecting means between the carrier arm and wall whereby the arm may move longitudinally in the film compartment, a boss supported by the wall, a shaft rotatably mounted in the boss, an arm carried by the shaft, motion transmitting means between the arm and slot of the downwardly extending projection of the carrier arm whereby the motion transmitting means may move beyond a dead center position in the slot to position the pressure plate housing adjacent the aperture plate and may move in the slot in the opposite direction from the dead center position to move the pressure plate housing away from the aperture plate.

a. In a motion picture projector having a main casing, a film compartment including a fixed wall, an aperture plate in the film compartment, 9. pressure plate housing in the film compartment, a carrier arm having a downwardly extending projection supporting the pressure plate housing, connecting means between the carrier arm and wall whereby the arm and housing may move longitudinally in the film compartment, a boss supported by the wall, a shaft rotatably mounted in the boss, an arm carried by the shaft, motion transmitting means including a pair of pivotally connected links between the arm and the down wardly extending projection of the carrier arm whereby the motion transmitting means may move beyond a dead center position in one direction to position the pressure plate housing adjacent the aperture plate and may move in the opposite direction from the dead center position to move the pressure plate housing away from the aperture plate.

' 5. In a motion picture projector having a compartment defined by at least one fixed member, an aperture plate mounted in the film compartment, a pressure plate housing slidably mounted on a fixed member in the film compartment and having generally vertically extending =engaging shoes, as housing carrier arm ineluding spaced projections positioned beneath and forwardly of the film-engaging shoes, 9. movable member carried by a fixed member in the film compartment, a connection between said movable member and the carrier arm comprising a cam carried by the movable member and positioned between the spaced projections of the carrier arm to engage one of said projections and move the pressure plate housing adjacent the aperture plate when the movable member is actuated in one direction and adapted when actuated in the other direction to engage the other of said projections and move the pressure plate away rrom the aperture plate, stop means associated with the movable member to limit rotational movement of the cam beyond a dead center position with the first-named projection to lock the pressure plate housing adjacent the aperture plate, and manually operable means to actuate the movable member.

6. In a commercial motion picture projector, a film compartment having a stationary wall, an aperture plate positioned in the film compartment, a plurality of spaced rods extending longitudinally in the film compartment, a pressure plate slidably mounted on the rods and having substantially vertically extending film-engaging shoes, motion-transimtting means to move the pressure plate longitudinally on the rods and in-' eluding relatively movable members positioned beneath and forwardly of said film-engaging shoes and connected to the stationary wall and to the pressure plate and movable in one direction beyond a dead center position to lock the pressure plate adjacent the aperture plate and movable in the opposite direction from the dead center position to separate the pressure plate from the aperture plate whereby film may be introduced between the film-engaging shoes and the aperture plate, stop means to limit movement of the relatively movable members beyond the dead center to define the locked position, yielding means between the film-engaging shoes and the stationary wall urging the relatively removable members toward said locked position, and manually operable means positioned in the film compartment beneath and forwardly or the filmengaging shoes to actuate one of said relatively movable members.

7. In a motion picture'projector having a film compartment including a fixed wall, an aperture plate extending transversely relative to the fixed wall, guiding means carried by the fixed wall and extending longitudinally of the film compartment, a pressure plate having a plurality of generally vertically disposed film-engaging shoes, connecting means between the pressure plate and the guiding means whereby the pressure'plate may move longitudinally of the film compartment on the guiding means to position the film-engaging shoes in operative or-inoperative positions ad- Jacent or spaced from the aperture plate, relatively movable members carried by the pressure plate and said fixed wall respectively and positioned in the film compartment beneath and 01- wardly or the film-engaging shoes to move the pressure plate longitudinally of the film compartment on the guiding means between said operative and inoperative positions, stop means positioned beneath and forwardly of the film-engaging shoes and operative after the relatively movable members pass beyond a dead center or etrelslit line position to limit movement or said relatively movable members beyond the dead center locked position when the pressure plate is moved to the operative position to place the filmengaging shoes adjacent the aperture plate, yielding means between the film-engaging shoes and the relatively movable members to maintain said relatively movable members in the locked position when the film-engaging shoes are in the operative position adjacent the aperture plate, and manually operable means positioned beneath and forwardly oi the film-engaging shoes to actuate one of said relatively movable members to move the pressure plate longitudinally of the guiding means to position the film-engaging shoes in the operative position relative to the aperture plate while nlm is held in threaded relation relative to the aperture plate.

8. A motion picture projector comprising a film compartment having a wall and an aperture plate, a pressure plate housing having a plurality of spaced generally vertically disposed film-engaging shoes slidably mounted on the wall and movable in the nlm compartment between positions adjacent and spaced IIOlIl the aperture plate, a downwardly extended projection carried by the housing, a shalt rotatably journaled relative to the wall, motion-transmlttmg means between said downwardly extended projection and shaft for controlling the position 01' the housing with rei'erence to the aperture plate, said motiontransmitting means comprising relatively movable members positioned in the film compartment beneath the film-engaging shoes and operable by rotational movement or said shaft, said members being movablerelative to each other beyond a dead center position when the housing is positioned adjacent the aperture plate to locl; the housing against unintended separation from the aperture plate, stop means to limit movement 01' said relatively movable members beyond the dead center position to establish said locked position, yielding means to maintain said relatively movable members beyond the 'dead center position, and manually operable means positioned beneath the film-engaging shoes to actuate said shaft. I

9. In a motion picture projector having a main casing, a film compartment having a fixed wall, a generally vertically disposed aperture plate, a film pressure plate including generally vertically disposed film-engaging shoes, a carrier for the pressure plate having a downwardly extending projection, connecting means between the carrier and the fixed wall whereby the film-engagin shoes may be moved longitudinally relative to the aperture plate in the film compartment between an operative position adjacent the aperture plate and a separated position to permit threading of mm into the pro ector, a support carried by the fixed wall beneath the film-engaging shoes, at shalt rotatably mounted in the support, motiontransmitting means including relatively movable members interposed between the projection of the carrier and the shaft whereby the film-engaging shoes may be locked in the operative position adjacent the aperture plate by movement beyond a dead center position or the relatively movable members by movement of said shalt in one direction and may be moved to the separated position by movement of the shaft in the opposite .direcso: and manually operable means to move the RAYMOND J. 

